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Enriched Instructor’s Manual to Accompany Understanding Nutrition, First Canadian Edition 6-1

Chapter 6Protein: Amino Acids

I F N O T H I N G E L S E , M Y S T U D E N T S S H O U L D L E A R N …

1. Protein is vital to the structural and working materials of all cells. Protein serves the following functions: (1) growth and maintenance of tissues, (2) acting as enzymes, hormones, and antibodies, (3) maintenance of fluid and acidbase balance, (4) assisting in the transport of nutrients, clotting of blood, and provision of eyesight.

2. Proteinenergy malnutrition may lead to kwashiorkor, marasmus, or a mix of the two diseases. Overconsumption of protein can lead to various health problems. Highprotein foods based on animalproducts tend to be high in saturated fats.

3. Not all proteincontaining foods are digested and absorbed in the same quantities, as different foods can be classified as being high or low quality protein sources.

L E A R N I N G O B J E C T I V E S

Students should be able to:

• LO 6.1: Discuss the various dietary amino acids and their classifications as essential, nonessential, or conditionally essential to the human body. [Remember/Understand]

• LO 6.2: Describe the digestion and absorption of protein and amino acids in the body. [Remember/Understand]

• LO 6.3: Discuss the various roles of proteins and amino acids in the body. [Understand]

• LO 6.4: Describe the process in which the body synthesizes new proteins and what factors can affect this process. [Understand/Apply]

• LO 6.5: Discuss the concept of nitrogen balance and compute the amount of protein needed based on the RDA. [Understand/Apply]

• LO 6.6: Compare the major forms of protein malnutrition and discuss why consuming excess protein is not recommended. [Analyze/Evaluate]

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• LO 6.7: Summarize the health advantages and disadvantages of various vegetarian diets and develop a day’s meal plan for a nutritious diet. [Understand/Apply]

• LO 6.8: Discuss protein and amino acid supplements, why people ingest them, and the possible implications they may have on health. [Understand/Apply]

W H Y I S T H I S C H A P T E R I M P O R TA N T T O S C I E N T I S T S A N D H E A LT H C A R E P R AC T I T I O N E R S ?

“Of special interest to...” symbol key: = HealthCare Practitioners = Science Majors

• When a protein is digested, it is broken down into single amino acids to be absorbed by the intestine. Some dipeptides and tripeptides are first absorbed into the cells lining the small intestine where they are split into single amino acids before they are absorbed into the bloodstream. Larger peptide molecules can escape the digestive process all together and enter into the bloodstream. Scientists believe that the larger particles provide the body with information about the external environment and may trigger allergies. Research in this area examines which of these larger molecules stimulate the immune response and what their role is in food allergies.

• Many people take protein and amino acid supplements for various reasons (to build muscle, to lose weight, to induce sleep, to cure infection, or to relieve pain). Scientists are studying whether these supplements actually work and if they are safe. Research is also needed on the longterm effects of consumption of amino acid supplements by healthy people and of the possible adverse effects.

• Many of the recommendations for protein intake are based on nitrogen balance studies that compare nitrogen loss by excretion with the nitrogen eaten in food. Scientists measure the body’s daily nitrogen losses in urine, feces, sweat, and skin under controlled conditions and then estimate how much protein would be needed to replace these losses.

• As many people have adopted highprotein diets in order to lose weight, the healthcare practitioner should understand the benefits and potential health risks involved with such a diet.

• The scientific community has observed that individuals who consume vegetarian diets often live a healthconscious lifestyle and have a reduced rate of chronic disease (obesity, cancer, heart disease). Researchers are now trying to factor out the contribution of a vegetarian diet from that of a healthconscious lifestyle.

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W H Y S H O U L D S T U D E N T S C A R E ?

• Students should know that proteins are unique among the macronutrients in that they are comprised of 20 different dietary amino acid and are classified as essential or nonessential. Amino acids link into long strands that coil and fold to make a wide variety of different proteins. Each type of protein has a distinctive sequence of amino acids and so has great specificity.

• Students should be aware of the processes involved in protein digestion. Digestion of protein involves denaturation by stomach acid, then enzymatic digestion in the stomach and small intestine to amino acids, dipeptides, and tripeptides. The cells of the small intestine complete digestion, absorb amino acids, and some larger peptides, and release them into the bloodstream for use by the body’s cells.

• Students also should have some insight as to the metabolic fate of amino acids. Amino acids are constituted into protein, metabolized for energy, or converted glucose or fat. An adequate diet should provide the full complement of essential amino acids.

• Students should be aware of the important role that proteins have in the body. The body requires dietary amino acids to synthesize new protein that function to provide cells structures and to serve as enzymes, ion channels, and receptors. Antibodies are proteins that defend against foreign substances in the body. Proteins help to regulate the body’s electrolytes and fluids. Proteins buffer the blood against excess acidity or alkalinity. Proteins have a role in blood clotting and prevent uncontrolled bleeding from injuries.

• Students should understand that the digestibility of protein varies from food to food, and cooking can improve or impair it. When insufficient carbohydrate and fat are consumed to meet the body’s energy need, the body breaks down protein primarily in skeletal muscle to provide much needed energy.

• It is important for students to be aware of how protein quality is assessed. The quality of a protein is measured by its amino acids, by its digestibility, or by how well it meets human needs. The protein value listed on a food label reflects the Protein digestibilitycorrected amino acid (PDCAAS) of the protein in the food. It is the method for measuring food protein quality. The best choices are egg white, ground beef, chicken, fatfree milk, and tuna fish.

• Daily protein requirements depend on body size and stage of growth. Students should be aware that the RDA for protein is 0.8 grams per kilogram of body weight for adults. It is also important for students to be aware that there are some differences in protein requirements that exist between different individuals, as athletes, infants, growing children, and pregnant women have higher needs.



• Students should know that there are adverse effects associated with the consumption of too little protein or too much protein in the diet. Proteindeficiency symptoms are always observed when either protein or energy is deficient. Health risks may occur with the overconsumption of proteinrich foods.

W H AT A R E C O M M O N S T U D E N T M I S C O N C E P T I O N S / S T U M B L I N G B L O C K S ?

1. Students often have difficulty understanding how enzymes function. As enzymes are critical proteins for basic physiological function, it is suggested that a discussion of enzyme action is incorporated into your lecture or seminar.

2. Students who are newcomers to nutrition often think that improving nutritional status is simply a matter of introducing more nutrients into the body. Some people think it is like dropping pennies into a jar—the more you put in, the more will be there. They need to appreciate that too little or too much protein can affect the overall nutritional status and health of an individual.

3. Students often have misconceptions about the protein content in plants compared to that of animals. Some of the misconceptions are as follows:

a) Plant proteins are not complete; they lack certain amino acids.b) Plant proteins are lower in quality than animal proteins.c) Proteins from different plant foods must be carefully mixed and eaten together

in the same meal. d) Plant proteins are difficult to digest.e) People cannot meet protein needs with plant proteins alone.f) Plant proteins are lacking in nutritional value because they are not balanced.

Handout 61 disputes these misconceptions.

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W H AT C A N I D O I N C L A S S ?

There are a variety of activities that can be done in class. Listed below are some activities that will help introduce the topic of nutrition, and the students to each other.

Classroom Activity 61: ChapterOpening QuizObjective: Introduction to chapter Class size: Any

Instructions: As a way of introducing any new chapter, give a quiz to the class. This is a quiz designed to be projected overhead. For details, please see Chapter 1, Classroom Activity 14.

Classroom Activity 62: Illustration of Enzymatic Action1

Key concept: Action of enzymes Class size: Any

Instructions: Compare a chemical reaction in the body to the union of a bride and a groom. The union requires a catalyst such as a priest or justice of the peace (JOP). The JOP has the power to unite the bride and groom and performs the ceremony, but afterwards, goes on unchanged.

Classroom Activity 63: Demonstration of Diffusion and Active Transport2

Key concept: Transfer of molecules across a membrane Class size: Any

Materials needed: Balloons (quantity = ½ the number of students)

Instructions: Divide the class physically in half with a space down the centre (the cellular membrane). Demonstrate diffusion by giving half the class small balloons to bounce up in the air (an area of higher concentration). A line of students can then be placed in the “membrane” space to demonstrate how active transport assists in the process of transferring the “molecule” balloons.

Classroom Activity 64: Protein Content of OvertheCounter Protein and Amino Acid SupplementsKey concepts: Protein sources; protein/amino acid supplements Class size: Any

Instructions: Protein powder supplements are marketed as providing substantial amounts of protein and enhancing athletic performance. Instruct students to bring index cards to the grocery or drug store and record the following regarding the protein powder supplements they find: name of supplement, cost of supplement, recommended daily dose, protein content of suggested dose, the %DV for protein that each dose provides. Discuss in class and generate suggestions for more safe, effective, enjoyable, and economical choices through food intake.

1 Activity provided by Robin S. Bagby, M. Ed., R.D., Penn State Nutrition Center2 Activity provided by Dorothy G. Herron, OrangeburgCalhoun Technical College



Critical Thinking Questions3

These questions will also be posted to the book’s website so that students can complete them online and email their answers to you.

1. Discuss the three differences between proteins and carbohydrates/fats. Articulate why these differences are important.

2. List the roles of proteins in the body and detail the importance of each role identified.

3. Many Canadians consume beyond the RDA for protein. However, there are many individuals that have difficulty acquiring enough food to feed themselves and their families, or are simply unable to eat enough to meet the RDA for protein. Many times, individuals having difficulty financially may consume inexpensive staples or leftovers from others. Discuss how the RD would go about assessing such an individual’s protein status. What suggestions would you have for this person to improve his or her protein intake and balance?

4. Protein consumption in adults could be considered a form of substance abuse in Canada. Why might this statement be true, and what are the health consequences of protein overconsumption?

5. The science of proteomics has allowed us to progress significantly in terms of understanding how proteins are sequenced and how errors in sequencing can impact an individual’s health. The Human Genome Project has also projected the biological sciences significantly further in understanding the human body and genetic conditions. Briefly, discuss how proteins might undergo a sequencing error and how that might impact one of the protein functions.

6. The Human Genome Project is forging the way for many scientists, including the nutrition science field. Discuss some of the pros and cons of this project for patients and professionals in the nutrition field.

Case Study4

Erin is a 28yearold professional woman who is 1.73 m (5 8 ) tall and vigilantly ′ ″maintains her weight at 53 kg (118 lbs) by following a lactoovo (nonfat milk and egg whites only) vegetarian diet that supplies approximately 1200 calories a day. With her understanding that protein should provide between 10 and 35 percent of her daily calories, she reasons that her daily intake of 40 grams of protein from milk, eggs, legumes, and nuts is adequate for her needs. She is concerned, however, that she has been sick more than usual and has experienced two stress fractures in her leg over the past three years while exercising.

1. Explain why Erin’s assumptions about her protein needs are unrealistic based on her current weight.

3 Contributed by Kathleen Rourke.4 Contributed by Barbara Quinn.

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2. Assuming a healthy weight for Erin is 64 kg (141 lbs), use the information from the How To Box on page 191 of this chapter to calculate her recommended daily protein requirement. Show your calculations.

3. What percentage of Erin’s energy comes from protein? Is this adequate? Why or why not?

4. Erin’s energy needs for a healthy weight are closer to 1600 calories a day. What are some consequences of her low calorie intake on her body’s need for protein?

5. How does Erin’s low intake of calories and protein contribute to her risk for osteoporosis?

6. Assuming Erin consumes 20 grams of protein from whole grains, vegetables, and legumes each day, calculate how she can meet the remainder of her protein needs with dairy foods and egg whites.

W H AT O T H E R R E S O U R C E S A R E AVA I L A B L E ?

You can look up information about government policy as well as any health condition that you are interested in learning more about. Consult the following websites to get reliable information on the following:

• Find out more about licensed natural health products (including proteins) at Health Canada: http://www.hcsc.gc.ca/dhpmps/prodnatur/applications/licenprod/lnhpdbdpsnheng.php

• To learn more about Canadian eating habits, including protein intake, go to http://www.statcan.gc.ca/pub/82620m/82620m2006002eng.pdf

• To find out more information about protein energy malnutrition go to the World Health Organization website: http://www.who.int/nutrition/publications/en/childgrowth_database_overview.pdf

A N S W E R K E Y F O R A L L I N S T R U C T O R S M A N UA L AC T I V I T I E S

Critical Thinking Questions5

These questions will also be posted to the book’s website so that students can complete them online and email their answers to you.

1. Answer: Proteins contain a nitrogen group along with carbons, oxygen, and hydrogen. These nitrogen molecules become part of the amino group, distinguishing proteins from carbohydrates and fats. This part of the protein is eventually excreted as

5 Contributed by Kathleen Rourke.


http://www.hc-sc.gc.ca/dhp-mps/prodnatur/applications/licen-prod/lnhpd-bdpsnh-eng.php

http://www.hc-sc.gc.ca/dhp-mps/prodnatur/applications/licen-prod/lnhpd-bdpsnh-eng.php

http://www.who.int/nutrition/publications/en/childgrowth_database_overview.pdf

http://www.statcan.gc.ca/pub/82-620-m/82-620-m2006002-eng.pdf


urea, a process that requires additional work of the kidneys, one limiting factor in overconsumption of proteins.

Proteins are very complex molecules that have primary, secondary, tertiary, and quaternary structures. Because they are much larger molecules than carbohydrates and fats, they are able to fold and configure themselves in unique ways. This allows them to perform many functions that are not performed by carbohydrates and fats.

Given the above, proteins are very susceptible to acid and heat and can be denatured readily. A denatured protein is not able to perform its given function. While fats can become rancid, neither fats nor carbohydrates become denatured in such a manner as to render them unable to perform their unique tasks or functions.

Also unique to proteins is their many functions as enzymes, fluid and acid–base regulators, transporters, antibodies, or parts of the body such as skin, muscle, or bones.

2. Answer: Growth and Maintenance of Body Tissues: One of the major roles for which proteins are noted or known is providing for growth and development of body tissues such as the muscles, skin, hair, etc. Proteins are also important in the repair of body tissues that are damaged or require replacement. Most consumers identify proteins with this function in the body; however, proteins have many more functions in the human body.

Functioning as Enzymes: Enzymes are important molecules in our bodies that are required for the many chemical reactions that release energy and allow our bodies to function. All enzymes are made of proteins; therefore, without protein, our bodies would be unable to carry out the chemical reactions required for life.

Maintenance of Fluid Balance: Fluid balance in and out of cells and within the blood is maintained by proteins. Proteins are very large molecules that do not normally cross cellular membranes. However, in times of critical illness, proteins are able to leak out, attracting water to themselves and causing a buildup of fluid or edema. When there is edema, the vascular system is less functional in its ability to carry all nutrients as well as oxygen around the body; therefore, the entire body becomes deprived of oxygen and nutrients. When this happens, depending on the length of time the situation lingers, tissues can and will die.

Maintenance of Acid–Base Balance: In the normal course of daily events of the body, the body works hard to maintain homeostasis. Proteins are an important part of this process through their work in maintaining acid–base balance. Proteins do so by attracting positively charged ions from hydrogen molecules to their negatively charged surfaces. Proteins can release these negative charges elsewhere in a basic environment, protecting themselves from denaturation.

Transportation of Many Substances throughout the Body: Proteins are especially good transporters of many substances, including nutrients such as vitamins and minerals, lipids (i.e., the lipoproteins), oxygen in hemoglobin, etc. Proteins are very large, complex, and multidimensional, allowing them to function in a variety of ways, some of which we are still discovering. In this regard, their role in transportation of

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nutrients about the body may still teach us more about the fundamentals of nutrition and micronutrient utilization.

Function as Antibodies: Antibodies are large protein molecules that are made by our bodies to help us fight against a particular disease or illness that is viral in nature. When an individual becomes ill with a virus, the virus leaves in the body materials or particles that are called antigens. Antigens are informational units about the virus that allow the body to make an antibody that can help the body fight against that particular virus with greater strength and speed. These antibodies are made of proteins from the body. Once the body has fought the disease, the work in producing the antibody from the antigen leaves behind memory information that stays in the body forever, producing “immunity” to that specific virus in the future. In this manner, each person’s body has a unique and wonderful ability to manufacture its own fighting army for viruses with proteins, for the most part! The body, of course, must be healthy and well nourished, and there are times when viruses (like AIDS) outwit our body’s unique defences.

Role in Energy: As discussed in earlier chapters, the body can break down protein to serve as a source of glucose and energy when needed. While there are many other more important roles for protein and utilizing protein for energy can be costly to those other roles, protein will be supplied as an energy source in times of need. In these cases, protein can be taken from the cells, body tissues, etc.

Other: Protein does serve in many other roles via its role in chemical reactions. For example, as outlined in your textbook, a cascade of events is required for the formation of a blood clot. A few of these events include the formation of fibrin, which is a stringy glob of protein fibres that will eventually lead to a collagen scar. Protein is also involved in vision, a sequence of events in which light permeates the cells of the retina. The protein molecule opsin responds to the light and decides how much light it will allow into the eye by changing the shape of the retina.

Clearly, protein is multifunctional, and vastly important to our bodies. Students should be able to gain a better understanding of the depth and breath of the role of protein in human function.

3. Answer: The average Canadian eats about 100 grams of protein/day compared to a recommended 50–60 grams, depending on gender and activity level (for those over 25 years). While protein intake is generally not a problem in Canadian culture, there are enough cases of protein malnutrition and individuals who are unable to consume highquality proteins in their diets that this question is posed to assist students in understanding the broad array of individuals they may come into contact with as practitioners.

The RD would generally perform multiple types of assessment to attain the best data for decision making. Therefore, the RD might investigate the following:

Dietary History: A food frequency and a threeday diet recall—with these assessments the RD is looking for types of protein eaten. The RD would want to



determine the quality of the protein, the frequency through an average week, and the amount. Does the patient have to combine proteins to make sure all essential amino acids are being consumed? Is the patient eating enough protein for his or her age, gender, weight, and height? Is the patietnt of a highrisk group that should be supplemented (i.e., pregnant, breast feeding, elderly, etc.)?

Social/Behavior History: Does the patient eat alone? Does the patient have any relatives or friends who can help with dietary issues? Has the patient had diet problems in the past? Do religion or cultural beliefs affect the diet? Has the patient lost any significant others in the recent past? Etc.

Medical History: Does the patient have any significant medical problems/issues that affect diet or ability to eat? Has the patient had any issues in the recent past? Is the patient on medications that affect his or her ability to eat? Drugnutrient interactions? Wounds? Woundhealing issues? Loss of hair, edema? What does the Nbalance study show? Is the patient in Nbalance? Was the patient assessed for protein malnutrition? Albumin? Does the patient have a history of heart disease, cancer, or bone disease? Any other diseases?

Physical Assessment: What does the patient look like? Does the patient look tired? Does the skin look dry? What about the turgor? Does the patient have edema? Is the hair thin, or are the nails weak? Does the patient have any unhealed wounds?

The goal here is for students to pursue a full assessment of the patient in an effort to acquire the most accurate information possible. While students may list other types of information, what is important is that students pursue multiple areas of assessment in an effort to ensure that they have many means of assessing protein intake and metabolism.

Recommendations for the patient might be as follows: Inexpensive yet nutrientrich sources of protein can include such food staples as peanut butter and legumes, and using powdered milk and oatmeal in meals such as meatloaf and hamburgers. Also advising that a patient utilize a food pantry, where such staples can be secured freely or for minimal cost, can stretch a budget a long way. Adding powdered milk or oatmeal to meat meals can not only stretch the meal but add to its protein value. This also holds true for adding beans to a meal.

4. Answer: As stated above, in Canada, consumers eat much more protein than is required for their bodies. There might be many reasons for this. One is that most consumers do not understand what an appropriate portion size for a “protein” is. Another is that many Canadians believe that protein is a miracle nutrient for everything that ails anyone. Many diets begin with the concept that more protein and less carbohydrate are good because many individuals have lost the notion that food is fuel for the body, not the next drug of choice. Given that we are fortunate to have a plentiful supply of food in Canada, food in general might be thought of as an abused substance; however, of all the nutrient categories, marketers see that protein appears to be the “miracle substance” sought by consumers that are desperate to win the battle of the bulge.

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The need for protein in the body has been thoroughly investigated for many years, and while nutrition is a young science and more can always be learned, it appears to be fairly clear that the healthy adult body’s need for protein is 0.8 g/kg/day or about 10–35 percent of energy intake. Over time, more work has been done on athletes; a higher goal has been established at 1.2–1.5 g/kg/day for athletes, given that there is much tissue breakdown with training, etc.

The average Canadian consumes 100–200 grams of protein a day. Consumers that adhere to diet fads promoting a highprotein and lowcarbohydrate intake consume well beyond this. Many consumers are led to believe that carbohydrates are “bad,” and proteins will “make ... people thin,” give people energy, and solve all sorts of problems. Advertisements for protein shakes, powers, pills, drinks, and bars abound. Yet consumers do not seem to understand the real roles of protein nor its limitations. And because it is a food, it might even be considered safer than a drug. Without hesitation due to their health, existing health problems, etc., many consumers will blindly follow a highprotein diet beyond their already highprotein diet. These diets seem attractive because, in many people’s viewpoint, consuming lots of steaks, eggs, bacon, etc. is preferable to eating moderately, exercising, and including fruits and vegetables.

In this manner, protein overconsumption might be analogous to a drug addiction because individuals do not see the problem as an addiction, theywill continue to pursue eating high volumes of proteins regardless of their health history, most individuals cannot go without meat proteins if given an ultimatum, most individuals cannot cut down on their consumption, and individuals who are meat eaters will indicate that there is no issue with their overconsumption with meat at the volume or level that they are eating this protein. These are all very similar signs to drug addiction.

Overconsumption of protein can be difficult on the body because metabolism of protein requires the excretion of the nitrogen group, which is the work of the kidneys. With consumption of a great deal of protein, the kidneys must work much harder to remove the urea from the body. Therefore, while generally protein digestion, absorption, and waste elimination are not an issue for the body, when large amounts of nitrogen must be removed from the body, this puts a great stress on the kidneys to remove the urea.

Those that ingest proteins from beef and other fatty sources add additional lipids or fats to their caloric load. If these calories are not used as energy, the body will store them as fat to be used as future energy. Additional lipids circulated in the body can result in the formation of plaque in the arteries. It is this plaque that can break free and perhaps result in a blood clot, a sudden heart attack, or heart failure of a loved one who had previously been healthy. While the continued buildup of plaque can close the artery and result in the requirement for heart bypass surgery or the death of tissue distal to the area where the artery was closed, in more recent years noted celebrities have died suddenly for no apparent reason from a plaque that was freed, causing a sudden heart attack in an otherwise “healthy” individual.



Protein is a kcaloriebearing nutrient. The more one eats, the more calories one provides to the body. If calories out are not balanced with calories in, excess calories are stored as fat. Frequently, individuals on highprotein diets believe that they will not gain weight. However, excess protein can mean excess calories if no exercise is part of the plan and the protein consumed is also accompanied with fat. Therefore, it is very important for consumers to understand that they must balance their calories in protein with exercise and that the best diet includes other types of nutrients, so that they are able to achieve a balance of all nutrients for optimal health.

5. Answer: Proteins are sequenced through a process that is quite complex, but is described in this chapter as a twostep process: transcription and translation.

A portion of DNA is needed to make a template for the mRNA (messenger RNA), which will transport the template code to the RNA on the ribosomes. In this first sequence, the DNA lines up with the mRNA, the mRNA coding with the exact sequence of the DNA. This process is called transcription of the template of DNA. The genetic code is being transcribed onto the template of mRNA. The mRNA dissociates with the DNA after it acquires the sequence and takes the sequence to the ribosomes in the cell cytoplasm, where synthesis of the protein occurs with help from the tRNA. The tRNA acquires amino acids from the materials around the cell and in the body fluids. The tRNAs then usher the amino acids into position to form the correct primary protein structure. This process is called translation in that the mRNA is translating to the tRNA the genetic code for the protein. Once the protein is completed, it is attached to its appropriate component, may undergo further processing, and moves on to assume its function.

Every protein is made for a very separate and different function and if, in the course of transcription, mRNA transcribes even one different amino acid, the protein may function poorly or not at all. Your textbook describes the misplacement of a valine in the position of a glutamic acid in the case of hemoglobin, which drastically alters the hemoglobin, resulting in sickle cell anemia. While your body carries out the process an amazing number of times a day, seldom does it error in its mission. Yet, on occasion, there are proteinsequencing errors that can be problematic to fatal—and due to only one amino acid. The Human Gemone Project’s work will allow scientists to further study these sequencing errors, predict them, and counsel and advise patients. The science of nutrition is on the verge of many new discoveries as well as challenges.

6. Answer: Students are being asked to use not only the information in the textbook to answer this question but also to develop a heightened understanding for how patients as well as professionals might react to the changing paradigms that form nutrition education programs with the Human Genome Project. As science advances, some patients and healthcare professionals remain steadfast or tried and true to the “don’t change what is not broken” theory, while others are anxious to try new things and forge new frontiers. The risks in this latter approach can be great indeed for both the patient and the professional, yet the payoff may be worth it. As a professional, the obligation to maintain standards of professional licensure, practice based on solid

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scientific evidence, and guide the patient accordingly must be carefully followed, despite unique therapies the patient might try. Therefore, in this question, the student must think about the advantages and disadvantages of gene profiling and consider where patients might believe there are great opportunities and great risks to their health. Professionals must weigh advances they may provide for a patient and decide when a patient is better off following a traditional therapy.

Pros for Patients: With the sequencing of the human genome, the potential to identify genetic predispositions to any variety of illnesses is advanced. Many scientists and medical professionals predict that with this possibility, patients will be provided with advance information as to potential medical issues and therefore these same patients can alter their lifestyle and health habits accordingly. Nutrition and dietary habits would be a primary area in which to seek improvements to prevent and/or reduce one’s risk for diseases of any sort. For example, if an individual is notified through their genetic profile that they have a gene for diabetes, this individual would pursue regular medical care, blood sugar monitoring, a diabetic nutrition program, etc. If the individual were to pursue such a program with care, he or she might be able to avoid becoming diabetic, minimize some of the complications of diabetes, and reduce the number of medications needed to control diabetes, given a strict program of medical and lifestyle interventions.

Outcomes from the Human Genome Project will allow patients to approach and plan their health, medical care, and lifestyle habits differently. In addition, the information can help patients planning to have children understand what types of genetic risks the fetus may have and make their family planning decisions based on such information. Again, in some cases, nutrition and nutrition education could be a vital part of improving the outcome or enhancing the outcome for these patients.

Data from the Human Genome Project will, over time, allow scientists to develop more effective treatments for patients with medical and nutritional illnesses and hopefully also work to advance a cure for illnesses. For instance, with the many types of cancer, the potential to understand the mutation and develop a treatment is conceivable.

Genetic counsellors work with patients who have family histories of inherited genetic disorders or fear the possibility of having a child with a genetic disorder and use the data available to them through blood samples and family profiles to assist a couple who is beginning to plan a family. Through their work, a couple can better understand their risks and the potential risks to the unborn fetus (for a genetic disorder) prior to trying to conceive. Should the genetic counsellor have information that dictates that a couple will most definitely produce a child with a genetic defect, the couple can then decide if they want to avoid pregnancy or initiate it knowing the outcome. They are then informed consumers and can prepare accordingly for the child, should they choose to have one.

Food Production: While there are already many examples of genetic engineering in the area of agriculture, the Human Genome Project does open the possibility for many new areas. Given that we are already capable of producing babies and animals in test



tubes, clearly the possibilities to develop, grow, and invent many types of food products are endless.

The goal in genetic engineering of fruits and vegetables and/or food products is to be able to develop and produce a “better” product by manipulating the genetic profile with the best profile possible and then producing the items in the best environment possible.

Cons for Patient: While the Human Genome Project does have the potential to provide enormous volumes of information to any particular patient, the overload of information and the technical detail of this information alone could be very overwhelming to some consumers. In addition, a consumer’s ability to fully understand such information is quite variable and does truly impact the outcome of successful nutrition education programs. How much information any one person needs and understands will be variable as will how much any one person will want this information. How will standards be set for the information provided? Also, who will be able to have access to the information? If individuals have genetic predispositions to diabetes or cancer and the information can be accessed by insurance companies, will these same individuals be denied access to critical care/disability/extended health insurance?

Genetic testing is an expensive undertaking. Who pays for this testing? Is it required or optional? If individuals find out that they have a genetic profile for a particular illness, how can a system be developed to optimize the chances that that a particular patient will follow the medical, nutritional, and lifestyle regime that is required to minimize the healthcare costs? Who would be responsible for oversight of that system? Should patients be required to follow any particular regime if they are genetically profiled for a particular disease? Should they be denied medical care if they do not follow their prescribed program?

While the information from a genetic profile could be quite helpful to an individual, some individuals may not want to be informed in advance of such information. Some individuals would “rather take their chances” and live life as it is played out. Critics of genetic counselling believe that it takes the spontaneity out of living and in some cases places individuals in a mode of “waiting for the other shoe to drop.” These individuals see having such information as a burden rather than a window of opportunity. Others believe that information from the Human Genome Project that is used to predict illness and better understand the health status of an individual is somewhat like “playing God,” as one may base their entire life on genetic data to the point of not really living. A person might be so focused and fearful of the genetic information that he or she adheres to a rigid lifestyle of exercise, nutrientrich foods, and frequent medical testing, yet dies from a car accident, never suffering any issues from the purported genetic illness.

Critics of genetic engineering believe that produce and food products that are a result of genetic engineering may not be exactly the same as those produced by nature, thus adding another unknown potential toxin into the food supply. In these cases it is a waitandsee situation, as any new element added to the food supply might take approximately 20 years to demonstrate any potential negative outcome in humans or

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in the environment. Therefore, there are a few more years to wait before the final verdict is in on genetic engineering of products, etc.

Pros for Nutritional Professional: The Human Genome Project has great potential for the nutrition field. First, the science of nutrition is actually quite young when compared to other sciences such as chemistry, physics, and biology. While much is known, so much more is still to be discovered. Through the Human Genome Project, the science and discoveries in nutrition are poised to be expanded. Second, in knowing of potential genetic mutations in humans, we learn how to treat and perhaps cure these diseases and we assist patients in pursuing medical care and lifestyles that support enhanced health. Certainly nutrition is primary to the majority of chronic diseases that plague Canadians. This factor increases the importance of nutrition, nutritional care, and nutrition education in health care and will increase the visibility of registered dietitians as part of the healthcare team.

To enjoy the opportunities, nutritional professionals must keep current in their knowledge of the advances in the Human Genome Project and impacts to the profession. Readings in the professional literature as well as a firm understanding of biochemistry and genetics will be essential to the growth of our profession. Expanded career opportunities will emerge from the Human Genome Project in the field of nutrition science, not only broadening career opportunities for students studying nutrition but also potential salary advances. Growth in collaborating with other healthcare professionals is necessary now and will continue. Physicians and other healthcare providers will look to the nutrition professional (registered dietitian) to work with patients on their diets in an effort to minimize or avoid any negative health consequence from a genetic inheritance.

Given the advance knowledge of a potential illness, the RD can work with patients to fully realize better health and better eating habits. Many individuals retain poor eating habits as a result of “denial” that they will be confronted with any adverse health event. However, if patients are assured that they are genetically coded for any particular disease, this knowledge can heighten their willingness to faithfully follow better nutritional habits. Given that nutritional habits are often similar among family members, if one family member retains positive dietary habits, the changes are very good that the remaining family members will also follow similar positive dietary habits. The potential for this type of trend throughout Canada could potentially reduce obesity, cardiovascular disease, and many chronic diseases that are a result of poor nutritional/dietary habits.

Genetic Engineering of Produce/Food Products: Mother Nature can be quite devastating with regard to crops, while multiple issues can result from breeding poultry, beef, pork, etc. for the food supply. In addition, growing crops and breeding animals take a great deal of land, space, and sometimes luck! Genetically engineering produce and other products for the food supply can take many of the risk factors out of the equation as well as support the growth of a genetically superior product. For example, instead of growing tomatoes on the land, there are now multiple processes for growing tomatoes, including growing them on water. Developments such as these



allow growers to avoid the changing nature of Mother Nature and control the growing environment.

In the case of poultry, beef, etc., breeders are able to control the genetics of the breed, enhancing the quality of the product. Additionally, the breeding is reliably done instead of waiting for Mother Nature again, in the event that the animals do not feel like breeding. The key here may also be the land that animals may require prior to slaughter. Cattle require a significant amount of land to graze in order to grow, putting great demands on the capabilities of the land to feed the population. Genetic engineering has the potential to provide answers to some of these truly significant environmental dilemmas.

Genetic engineering also has the potential to provide consumers with new, flavourful, and healthful food products not formerly available through their innovation and creation. Consumers look for new food products that “break neither the bank nor the waistline” and science may provide some of those answers. Food manufacturers work hard to provide consumers with options. Though they are not genetically engineered, products such as the fat replacers and alternative sweeteners are examples of recently developed diet alternatives. It is important for the RD to stay current with all new products as consumers will challenge the RD about them.

Cons for Nutritional Professional: Innovation is a wonderful thing but what happened to “leaving well enough alone and living for today”? As noted with the consumers or patients, even if genetic information is available to them to assist them in making the most informed medical decision, patients may well want to be uninformed. And, as with the patients, who then becomes responsible for the number of issues that surround such decisions? While some patients may be more motivated to follow strict dietary plans if they know that they are genetically prone to a heart attack, others may believe that there is nothing that is going to stop it, so why not “live for today”?

Nutrition education/counselling for a population that has available to them a massive amount of genetic information can be complex without some standard guidelines. It will be important for Dietitians of Canada and RDs to prepare policy guidelines for patient counselling and education with genetic information. Should practitioners practise consistently if patients want to experiment, or should practitioners work with each individual patient and his or her ability to understand the information given to him or her and ability to use it? An excellent example would be the sports nutrition movement. The American Dietetic Association’s position on supplementation at the beginning of significant endurance events where athletes were seeking nutrition counselling was that it should not be encouraged. However, RDs who worked with professional and worldclass athletes knew that if they were to be taken seriously, they had to be open to vitamin and ergogenic supplementation or the athlete would go elsewhere. Thanks to the science of sports nutrition, we now know that endurance athletes do need a bit more protein to support tissue repair and that while some ergogenics still need much more research, there is some evidence to support some of their use. Finally, the field advances every day, and those RDs who took risks in the early days were at the forefront of this new field.

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Case Study Answers1. Protein needs are based on “healthy body weight.” Erin is underweight so her actual

weight is not a good parameter for calculating her protein needs.

2. RDA for protein = Weight in kg × 0.8 = 64 kg × 0.8 grams per kg = 51 grams protein per day.

3. 40 grams protein × 4 kcal per gram = 160 kcalories divided by 1200 kcalories per day = 13.3 percent of her daily calories from protein. Although this falls into the recommended percentage of calories from protein, it is not adequate because the requirement for protein assumes that adequate calories to meet dietary needs are consumed. Erin is consuming inadequate calories.

4. An inadequate intake of calories forces the body to use protein to meet energy needs and less is left to meet the body’s protein needs. Immune function and bone loss are two important consequences of inadequate protein.

5. Protein as well as calcium is needed for bone health. When calories are restricted, essential protein is used for energy needs and less is available for essential functions like synthesis of collagen, the primary protein in bone.

6. 750 mL (3 c) milk × 8 g protein/250 mL = 24 g protein + 1 egg white = 7 g protein = 31 g + 20 g from vegetables, legumes, and vegetables = 51 g protein per day.

Worksheet Answer KeyWorksheet 61: Nitrogen Balance Calculations1. a. 135/2.2 = 61 kg; 61 × 0.8 g/kg = 49 g

b. NI = 38/6.25 = 6.08; NL = 8 + 4 = 12; NB = 6.08 – 12 = 5.92 c. Negative nitrogen balance. d. Protein recommended protein intake is 49 g/day, but patient only took in 38 g.

Patient took in too little protein, but even with a normal protein intake, the patient would still be in negative nitrogen balance.

2. a. 142/2.2 = 65 kg; 65 × 0.8 kg = 52 g b. NI = 69/6.25 =11.04; NL = 6+4 = 10; NB = 11.04 10 = 1.04 c. Positive nitrogen balance. d. Protein recommended protein intake is 52 g/day, but patient took in 69 g. Patient

took in too much protein, but even with a normal protein intake, the patient would still be in positive nitrogen balance.

Worksheet 62: Significance of Amino Acids

Patient Essential NonessentialConditionally

Acquired Sequencing Error



Newborn baby diagnosed with PKU

X Phenylalanine ↑

X Tyrosine↓

X Autosomal recessive disorder

Elderly female diagnosed with PEM

X* Variable amino acids levels seen →usually decreased



Adult male with partial thickness burns over 20% BSA

X Branched chain amino acids (leucine, valine, and isoleucine) Glutamine

Reference: http://ageing.oxfordjournals.org/cgi/reprint/26/6/457.pdf

Worksheet 63: Quick Protein Intake AssessmentAnswers will vary.

Worksheet 64: Chapter 6 Crossword Puzzle1. dipeptide

2. buffers

3. acidosis

4. polypeptide

5. proteases

6. alkalosis

7. tripeptide

8. pepsin

9. synthetase

10. deamination

Worksheet 65: Proteins from Foods (Internet Exercise)1. False

2. True

3. a) 4 grams of protein; b) 21 grams of protein; c) 16 grams of protein; d) 11 grams of protein; e) 8 grams of protein

4. True

5. False

6. False

7. True

18

http://ageing.oxfordjournals.org/cgi/reprint/26/6/457.pdf


WO R K S H E E T AC T I V I T I E S

Worksheet 61: Nitrogen Balance Calculations

Nitrogen Balance Studies

Nitrogen Balance (NB) = Nitrogen Intake (NI) – Nitrogen Loss (NL)NB > –5 g/day = severe stress

NB = 0 to –5 g/day = moderate stress

NI = Protein intake (g/day ÷ 6.25)NL = Urinary Urea Nitrogen (UUN, in g/day) + 4 g

UUN is derived from a 24hour urine specimenNormal range = 6–17 grams/24 hours

+NB = anabolic state with a net gain in body protein–NB = catabolic state with a net loss in body protein

For each of the following examples:a. Calculate the patient’s recommended protein intake. b. Calculate the patient’s NB.c. Indicate whether the patient is in + or – nitrogen balance.d. Discuss the implications of the findings.

1. 45yearold female, weight 135 lbs, protein intake of 38 grams, and UUN = 8 grams

a.b.c.d.

2. 89yearold male, weight 142 lbs., protein intake of 69 grams, and UUN = 6 grams

a.b.c.d.



Worksheet 62: Significance of Amino Acids

Amino Acid Concept Application

Essential Must be provided to the body in that form; absence is incompatible with life

Nonessential Can be made by the body using other sources

Conditionally acquired In times of stress and/or growth and maturation events, nonessential amino acids now become essential to the body

Sequencing errors Congenital disease such as sickle cell anemia is an example of a genetic disease arising from alterations in genetic coding (amino acid substitution)

For each of the following clinical examples, indicate whether the patient is at risk to develop a problem related to amino acids.

Patient Essential Nonessential

Conditionally Acquired

Sequencing Error

Newborn baby diagnosed with PKU

Elderly female diagnosed with PEM

Adult male with partial thickness burns over 20% BSA

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Worksheet 63: Quick Protein Intake Assessment

Most people in Canada and the United States receive more protein than they need. This is not surprising considering the abundance of food eaten and the central role meats hold in the North American diet. Using your food diary from the Nutrition Portfolio in Chapter 1, estimate your protein intake for the day. Multiply the number of servings you consumed by the estimated protein per serving to approximate your total protein intake.

Food GroupsServings

ConsumedEstimated Protein

Totals

Grains 3 grams/serving

Vegetables 2 grams/serving

Fruit 0 grams/serving

Milk, yogurt, and cheese

8 grams/serving

Meat, poultry, fish, dry beans, eggs, and nuts

7 grams/ounce

Oils, solid fats, and added sugars

0 grams/serving

Total estimated protein intake:

The protein RDA for young adults (19 to 24 years old) is 46 grams for women and 58 grams for men. Health experts advise people to maintain moderate protein intakes—between the RDA and twice the RDA.

1. Do you receive enough, but not too much, protein daily?

2. How often do you select plantbased protein foods?



Worksheet 64: Chapter 6 Crossword Puzzle

1 2

3

4 5

6

7

8

9

10

Across Down

4. Many (10 or more) amino acids bonded together

6. Abovenormal alkalinity (base) in the blood and body fluids

7. Three amino acids bonded together9. An enzyme that enables two or more

substances to form a more complex structure

10. Removal of the amino (NH2) group from a compound such as an amino acid

1. Two amino acids bonded together2. Compounds that help keep a solution’s

acidity or alkalinity constant3. Abovenormal acidity in the blood and

body fluids5. Enzymes that hydrolyze protein8. A gastric protease

22


Worksheet 65: Proteins from Foods (Internet Exercise)

Go to the following website to answers questions 1–3: http://www.cdc.gov/nutrition/everyone/basics/index.html. Do not close the window until you have answered all of the questions.

On the website, click on Protein to answer questions 1 through 3.

1. Complementary proteins do not include all of the essential amino acids.a. Trueb. False

2. Research studies have changed the idea that foods must be eaten at the same meal to achieve the concept of complementary proteins.a. Trueb. False

3. Match the amount of protein with the food selection.a. 125 mL (½ c) of milk _____ 4 grams of proteinb. 90 g (3 oz) of meat _____ 8 grams of proteinc. 250 mL (1 c) of dry beans _____ 11 grams of proteind. 250 mL (8 oz) of yogurt _____ 16 grams of proteine. 125 mL (½ c) of dry beans _____ 21 grams of protein

Use the following website to answer questions 4–7: http://teaching.ucdavis.edu/nut10public/quiz/proteinquiz.html. Take the quiz, and use the information/answers obtained to answer the following questions. Do not close the window until you are done answering the questions.

4. The daily RDA requirement for protein is 0.8 g/kg.a. Trueb. False

5. Proteins can be used interchangeably in the body because they have similar structures.a. Trueb. False

6. Yogurt is an example of an incomplete protein.a. Trueb. False

7. The Daily Value for protein is 50 grams.a. Trueb. False


http://teaching.ucdavis.edu/nut10public/quiz/proteinquiz.html

http://www.cdc.gov/nutrition/everyone/basics/index.html


Handout 61: Plant Proteins in Human Nutrition: Myths and Realities

Myth Reality

Plant proteins are not complete; they lack certain amino acids.

Most dietary combinations of proteins are complete; certain food proteins may be low in specific amino acids.

Plant proteins are lower in quality than animal proteins.

Protein quality depends not only on the source but also on the dietary mixture of plant proteins; plant proteins can be as high in quality as animal proteins.

Proteins from different plant foods must be carefully mixed and eaten together in the same meal.

Proteins do not have to been eaten at the same meal; the mixture over a day is important for nutritional value.

Plant proteins are difficult to digest. Depending on the source and method of food preparation, plant proteins can be easy to digest.

People cannot meet protein needs with plant proteins alone.

Plant protein or animal protein can provide adequate protein for human needs.

Plant proteins are lacking in nutritional value because they are not balanced.

Plant proteins do not create a practical problem in terms of balance; possible imbalances are observed in amino acid supplementation.

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Handout 62: PDCAAs of Selected Foods

Food PDCAAs1

Egg white 100

Ground beef 100

Chicken hot dogs 100

Milk protein (casein) 100

Fatfree milk powder 100

Beef salami 100

Tuna 100

Soybean protein 94

Whole wheat pea flour 822

Chick peas (garbanzos) 69

Kidney beans 68

Peas 67

Sausage, pork 63

Pinto beans 61

Rolled oats 57

Black beans 53

Lentils 52

Peanut meal 52

Whole wheat 40

Wheat protein (gluten) 25

1 Proteins with ideal digestion and amino acid balance are given a score of 100; others are scored against this standard.2 An example of mutual supplementation. Combining whole wheat and pea flours yields a protein with a higher PDCAAs than that of either product alone.



Handout 63: Do You Get Enough or Too Much Protein Each Day?

1. Calculate your protein need:

a) Your weight = _________ poundsb) To convert your weight into kilograms:

________ pounds ÷ 2.2 pounds per kilogram = ___________ kilogramsC) DRI recommendation for adults: 0.8 g of protein/kg of body weight/day

_________ kg body weight × 0.8 g protein/kg of body weight = __________This is your recommended amount of protein per day.

2. Record a day’s worth of your food and drink intakes in a table like the one below.

Example of part of a day’s intake:

Meal Food and AmountProtein (grams)

Breakfast 250 mL(1 cup) plain instant oatmeal 6 g

1 banana 1 g

30 mL (2 tablespoons) sugar 0 g

250 mL (1 cup) orange juice 2 g

Lunch 2 fast food bean burritos 14 g

375 mL (12 oz) can Cherry Coke 0 g

You can determine your protein intake in several different ways. You can use the food composition table in APPENDIX H of the textbook to help you calculate the total grams of protein. You can also use software such as Diet Analysis Plus that your instructor has chosen for the course. These programs can automatically calculate the protein amounts.

Analysis: Was your protein intake higher or lower than your recommended amount? If it was higher or lower, suggest ways that you could change your daily intakes to bring your daily protein intake closer to your recommended level.

You can repeat the exercise, but design an improved diet and enter the information into a second table like the one above. Check to see whether your new diet brings your protein intake closer to the recommended levels.

Contributed by Mary Ellen Clark.

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Handout 64: Where Are the Proteins? Meats versus Vegetables as Sources

People who eat animal products but do not eat meat are called lactoovo vegetarians. They eat eggs and dairy products such as milk, cheese, or eggs. People who eat no animal products are called vegans. They eat beans, grains, nuts, fruits, and vegetables. Both types of vegetarians eat this way for many years and are as healthy as anyone else. How do they do it?

Can you get enough proteins if you don’t eat meat? What if you don’t eat any animal products? How can you find out? You can try some diet planning and diet analysis to find out where the protein is found in foods.

Design a oneday diet as if you are a meat eater, lactoovo vegetarian, or vegan. You can analyze the food using the food composition table in APPENDIX H of your textbook or by using Diet Analysis Plus. Prepare a table (or computer printout) including each food/amount, grams of protein, grams of saturated + trans fats, and grams of unsaturated fats (polyunsaturated + monounsaturated).

Example of part of a day’s intake for a vegan:

Food and AmountProtein (grams)

Sat. + trans fat (grams)

Poly. + mono. fat (g)

2 small whole wheat bagels 24 g 0.6 g 1.6 g

500 mL (2 cups) apple juice 1 g 0 g 0 g

2 slices whole wheat bread 6 g 0.6 g 1.6 g

1 vegan burger patty 16 g 0 g 0.8 g

57 g (¼ cup) tomato, sliced 0.25 g 0 g 0.2 g

57 g (¼ cup) onion, sliced 0.5 g 0 g 0 g

Can you get enough (or too much) protein if you eat a lactoovo vegetarian diet? A vegan diet? If you did not get enough protein for your body weight, suggest ways that you could get more. Consider trying food substitutions or adjusting portion sizes.

Compare the fat content of the three diets. Which of your diet plans most closely followed dietary recommendations for the amounts and types of fats as presented in your textbook?

Contributed by Mary Ellen Clark.


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